Improved electrochemical storage of lithium into multi-walled carbon nanotubes by light irradiation

Multi-walled carbon nanotubes (MWNTs) were synthesized by catalytic decomposition of acetylene at 750 °C over silica supported cobalt catalysts. The effects of xenon light irradiation on electrochemical storage of lithium into MWNTs were investigated by various electrochemical testing techniques. The as-prepared MWNTs demonstrate a high reversible capacity of 237 mAh g−1 with good cycling stability at a current density of 30 mA g−1. Upon illumination, the reversible capacity for the MWNTs reaches about 270 mAh g−1 at the initial cycle, and remains above 250 mAh g−1 after 25 cycles. The results from CV and EIS analysis reveal that the light irradiation on the MWNTs may allow easy insertion/extraction of lithium into/from the nanotubes, and therefore leading to higher reversible capacity than that without light irradiation.